1. Field of the Invention
The present invention is directed to a method and apparatus for quickly and effectively drying surfaces including asphalt, concrete, and earthen surfaces without overheating the surface such as to damage the surface material or surface finish. The invention has particular utility in the area of drying racetrack surfaces.
2. Description of the Related Art
Motorized racing has become a very popular entertainment form in the United States and abroad, drawing audiences of up to many thousands of people at a racing event. Motorized racing also takes a number of forms including motorcycle racing, NASCAR®, drag racing, and others. All of these forms of racing feature motorized vehicles traveling at a high rate of speed, and the condition of the track is a prime concern at such an event. All of these forms of racing are heavily dependent on the availability of a track surface that is dry and uniform in order to achieve commonly accepted margins of safety. When rain is experienced, a race has to be delayed or temporarily stopped, which of course, causes a considerable inconvenience for racers and spectators alike. It is important after a brief experience of rain that the track be quickly dried so that the race can resume.
Track surfaces vary widely in motorized racing. Most large commercial tracks feature an asphalt surface, although concrete or other surface materials are possible. Dirt tracks are also common, especially at smaller racing venues. In addition to surface material variations, racing tracks vary widely in design with most featuring banking of the track in the turns. The degree of banking as well as the tightness of the turns varies greatly from track to track. In addition, since racing tracks are dispersed around the world, environmental conditions often play a significant role in track design, and characteristics such as humidity and the likelihood of rainfall add variables that must be taken into consideration in track maintenance.
In order to dry a track after rain concludes, a track dryer may be used to dry the surface of the track to an acceptable level of dryness such that racing can resume. A variety of instruments has been used in the past with varying degrees of success. One kind of track dryer that has been employed is the Jet Dryer by Eagle Enterprises. The Eagle device is essentially a jet engine mounted on a wheeled frame and oriented to blow jet exhaust directly onto the track surface. Although effective in drying most surfaces, the Eagle device suffers from significant drawbacks, including the very high cost of jet fuel. The device may be adapted to use gasoline, but still suffers from the disadvantage that it uses an enormous amount of fuel in relation to the amount of area dried. In addition, due to the nature of the device, the jet dryer functions very poorly on a banked surface such as race track turns. Severe noise pollution is also a significant drawback. In addition, the jet dryer is inadequate on a dirt surface as it creates an enormous amount of airborne dust.
Another system widely used features the application of a direct flame placed upon the track surface, essentially scorching the moisture out of the track. Other systems occasionally used are loosely based on devices designed to heat asphalt for repair purposes. As such, they are generally large and result in the application of a high degree of heat directly upon the surface. These systems are largely inadequate as they can cause considerable damage to the track surface by drawing and burning petroleum components from the asphalt. If an asphalt surface is repeatedly dried by such a means, over time, the upper surfaces of the asphalt will become brittle and deteriorate due to the drawing of oil from the asphalt. In addition, systems featuring a direct flame cannot be used to clean up an oil spill or an oil slick caused by an accident. It would be advantageous to have a track drying mechanism that can also be used to clean an oil spill from the track.
Examining the patent art for track heating or drying mechanisms, the bulk of such art relates to devices for reconditioning asphalt pavement. As such, these patents attempt to uniformly and homogeneously heat the pavement to a temperature that softens it for removal and reprocessing without creating hot spots. Excessively high temperatures in this process may result in smoking which is the removal of some of the petroleum components of the asphalt. Typical of the relevant art and perhaps the most pertinent is U.S. Pat. No. 4,561,800 by Hatakenaka et al. which uses hot air convection to soften the asphalt. In its preferred embodiment, Hatakenaka uses a heat source, a temperature sensor, a large enclosure in close proximity to the asphalt, adjustable vents within the enclosure, and a blower to move the air. The temperature sensor is used in a feedback loop to adjust the amount of heat added to the air.
Hatakenaka features ducting to connect these elements in a nearly closed circuit with a discharge port located above the heat source. The fan pushes the air past the heat source with some air leaving through the discharge port. Next, the air travels past the sensor on its way to the vents within the large enclosure where the heated air is directed evenly towards the asphalt while being mostly retained within the large enclosure. The heated air is drawn from the enclosure back into the ductwork along with some ambient air from the edges of the enclosure, passes through the blower, and flows past the discharge port on its way to the heat source to be reheated for the next pass at the asphalt.
Very similar to Hatakenaka are U.S. Pat. No. 6,371,689 B1 by Wiley et al. and U.S. Pat. No. 4,599,922 by Crupi et al. Wiley also uses hot air convection in a mostly closed flow path with feedback temperature controls to soften the asphalt. However, Wiley '689 monitors the temperature of the air after it is drawn back off of the pavement from the enclosure but before it enters the blower. The stated purpose for this is to use the temperature of the air coming off the pavement as a proxy to monitor the temperature of the pavement so as not to exceed a critical temperature for the pavement. Crupi predates both Hatekenaka and Wiley '689 and while it does use an essentially closed flow path and a large enclosure, Crupi places the blower after the heat source and does not use a feedback control loop on the heat source.
The U.S. Pat. No. 4,749,303 by Keizer et al. and U.S. Pat. No. 5,895,171 by Wiley et al. use radiant heat to soften the asphalt. Keizer forces a fuel-air mixture through a refractory blanket to burn on the blankets underside. The blanket then radiates heat to the pavement. Wiley '171 utilizes both convection heat and radiant heat transfer to heat the pavement. In Wiley '171, heated air circulating in an essentially closed loop passes through a perforated plate located near the pavement. The air heats the plate which then radiates to the pavement and then the air flows to the pavement for convection heat transfer to the pavement.
Another related patent from a field slightly different from asphalt rework is U.S. Pat. No. 5,020,510 by Jones. Jones uses hot air diffused into a large downwardly open enclosure on wheels to apply heat to large areas of ground. The apparatus can be towed and the temperatures are sufficient to kill grass, weeds and seeds on the ground.
All of the prior art devices described above suffer from one or more drawbacks that severely limit utility with respect to economical and effective track drying. Many of the prior art devices utilize direct flame or excessive heat which precludes the device from being used to clean an oil spill from the track. Furthermore, some of the devices are excessively heavy and bulky and cannot be maneuvered on a banked track. As mentioned earlier, many of the prior art devices actually damage the surface of the asphalt tracks by drawing petroleum components from the asphalt which damages the surface over time. In addition, the prior art devices are generally ineffective to use on drying a dirt track. What is needed is a track drying device that is economical to operate, easy to maneuver, relatively lightweight, and overcomes the various disadvantages in the prior art noted above. The present invention achieves those purposes entirely.